Finned hollow article



Feb. 25, 1964 v.1. C OSPEN FINNED HOLLOW ARTICLE 2 Sheets-Sheet 1 FiledJune 15, 1959 JyQI , INVENTOR. JEA N COSPEN ATTORNEYS BY W Feb. 25, 1964Y J. cosPEN 3,121,940

- FINNED HOLLOW ARTICLE Filed June 15, 1959 2 Sheets-Sheet 2 INVENTOR..TE A A/ (aspen BY M. 52 I 7| United States Patent 3,121,940 FZNNEDHULLQW ARTICLE Jean Qospen, Cachan, France, assignnr to in MathiesonChemical Corporation, East Alton, IiL, a corporation of Virginia FiiedJune 15, 1959, Ser. No. 823,244 Gaines priority, application Frmce June15, 1958 5 Ciahns. (Cl. 29-1573) This invention relates to hollowarticles and more particularly to a heat exchanger having integral fins.

In accordance with the teachings contained in United States Patent No.2,690,002, issued on September 23, 1954, a pattern of weld-inhibitingmaterial is applied to a weldable surface of a metal sheet over which asecond sheet is superimposed. The sheets are secured together to preventrelative movement between them and then pressure-welded together, as byrolling, in their adjacent areas not separated by the weld-inhibitingmaterial. Subsequent to the pressure welding operation, the resultantsheets are usually softened by annealing and the unjoined portiondefined by the pattern of weld-inhibiting material is outwardly expandedby injecting therein a fluid pressure of sufficient magnitude topermanently distend the sheets in the area adjacent the applied patternof weld-inhibiting material. The expanded portions define a system ofpassageways for fluid fiow. The aforesaid process is equally applicableto any number of superposed sheets having interposed between them anappropriate pattern of weld-inhibiting material. The resultant panelobtained by the aforesaid process is characterized by the absence of anyinterface between the complementary sheets forming the resultant panelproviding improved characteristics when used as a heat exchanger.

It is often desirable that the heat exchange tubing for boilers,refrigerators, condensers and the like be provided with external fins.Such heat transfer fins are usually brazed or soldered on the tubingexcept Where the tube structure is very heavy and permits the fins to becast, extruded, or rolled. However, especially where the tubing is ofthe fiat or oblong sheet metal type, thin walled tubing and the fins areusually brazed or soldered together. This is not only expensive and timeconsuming, but frequently fails to result in a rigid and efficientjoint. Generally, a brazed or soldered joint is of reduced heat exchangeefiiciency for lack of unimpeded heat transfer through the joint.Another heretofore known method of forming fins is a helical rollingmethod which, however, has the disadvantage of requiring a fully formedround tube blank together with an internal mandrel and which has thefurther disadvantage of requiring a considerably thick tube wall andcomplicated apparatus and controls for the proper extension of integralfins. This prior method is not readily adapted to formation of fins inconjunction with relatively thin sheet metal walls.

Accordingly, one object of this invention is to provide a simple, lowcost and improved design of finned heat exchangers.

Another object of this invention is to provide a novel and improvedrelatively thin and economical panel structure having integral flangesor fins suitable for various purposes such as strengthening or fasteningfor heat exchange.

Another object of this invention is to extend the surfaces of a heatexchanger fabricated according to the process of the aforesaid patentWithout increasing the weight of the unit.

Other objects and advantages will become more apparent from thefollowing drawings and description in which:

FIGURE 1 is a plan view of a sheet of metal having 3,121,940 PatentedFeb. 25, 1964 applied to it patterns of weld-inhibiting materialaccording to one embodiment of this invention;

FIGURE 2 is a plan view of an embodiment of this invention illustratinga ssytem of passageways distended in accordance with the pattern ofweld-inhibiting material applied in FIGURE 1;

FIGURE 3 is a plan View illustrating a successive step in thefabrication of the finned heat exchanger from the embodiment of FIGURES1 and 2; and

FIGURE 4 illustrates one configuration of a finned heat exchanger thatmay be obtained from the panel depicted in FIGURE 3.

In accordance with this invention a pattern of weldinhibiting materialis applied to a clean Weldable surface 1 of a metal sheet 2 so as todefine a desired system of passageways 3. This pattern includes a seriesof stripes 4 interconnected at alternate adjacent terminal portions bylateral stripes 5. One of the longitudinal stripes 4, closest to alateral edge, is connected to the end of a lateral stripe 6 whose otherend extends longitudinally to the edge of sheet 2 by means of a stripe7. Another longitudinal stripe 4, closest to the other lateral edge, isconnected to a stripe 8 which extends toan edge of sheet 2.

A plurality of additional patterns of Weld-inhibiting material is alsoprovided on surface 1 of sheet 2. As illustrated in FIGURE 1 theseadditional patterns are applied in a rectangular configuration. A pairof these rectangular configurations, a long one 9 and a short one 19,are provided between each pair of adjacent longitudinal stripes 4-.However, it is to be understood that a singular rectangular pattern ofweld-inhibiting material can also be used. In addition, laterallyextended rectangular patterns of weld-inhibiting material 11 and 12 areapplied adjacent each side of laterally extending stripe 6.

Subsequent to the application of the weld-inhibiting material on thesurface of sheet 2, a second sheet is superimposed on its surface 1 andpressure welded thereto in the areas not separated by weld-inhibitingmaterial in accordance with the aforesaid patent. The resultant pressurewelded panel 13 is illustrated in FIGURE 2 with the unjoined portionsdefining the desired tubular passageways 14 expanded to facilitate thedescription of this invention. However, it is to be understood that theaforesaid passages may be either distended or undistended forfabrication of the desired structure of this invention.

Subsequent to the expansion of passages 14, the resultant unjoinedportions defined by the rectangular configurations of broken lines 19are bisected by slitting at 15, by any appropriate means such asshearing or punching or the like, in the direction lengthwise of thelongest dimension of the rectangular configuration. Two additional slits16 are provided at the terminal portions of slits 15 is a directionperpendicular thereto along the edges of the rectangular configuration19. The resultant series of slits comprises a long slit 15 terminatingperpendicularly in the mid-point of a short slit 16, forming in effect aT-shape at each end of slit 15. In each instance, slits 15 and '16extend through both complementary portions of panel 13 adjacent therectangular unjoined area resulting for the application ofweld-inhibiting material. After the panel has been slitted, theaforesaid complementary portions are then separated from each other bybending along opposite unslitted edges of rec tangle 5 so as to extendin opposite directions out of the plane of the panel to form fins orflanges 17 leaving openings 18' in the areas of the panel from which thefins or flanges 17 were formed.

Although a specific rectangular configuration for the finned patternsand a specific means of forming them has been described, it is to beunderstood that the fin patterns may be of any desired irregular orcomplex design. The fins may also be formed from the fin patterns byfirst expanding them followed by milling off the crest of the expandedfin patterns. And, although the primary purpose of this invention isdirected to extending the heat exchange surface of a heat exchanger byprovision of fins integral with the exchanger, it is to be understoodthat the resultant fins may be employed as flanges for fastening,spacers or any suitable purpose.

Although the invention has been described with reference to specificembodiments and details, Various modifications and changes, within thescope of this invention, will be apparent to one skilled in the art andare contemplated to be embraced within the invention.

What is claimed is:

1. A method of making a finned hollow panel comprising interposingbetween superposed sheets of metal a first pattern of weld-inhibitingmaterial and at least one separate second pattern of weld-inhibitingmaterial, said first pattern corresponding to a predeterminedconfiguration of fluid passages and said second pattern defining a finpattern with said second pattern spaced from the peripheral edges ofsaid sheets, pressure welding said superposed sheets in the areas notseparated by said weldinhibiting material, and cutting at least onefirst slit through the complementary portions of said panel adjacentsaid second pattern, cutting at least two spaced second slits at spacedpoints on said first slit and spaced apart a distance to providesubstantial fin surface, each of said second slits traversing saidsecond pattern laterally relative to said first slit, and separatingbetween adjacent second slits said complementary portions to extend inopposite directions out of the plane of said panel whereby saidseparating forms an opening through said panel.

2. A method of making a finned hollow panel comprising interposingbetween superposed sheets of metal a first pattern of weld-inhibitingmaterial and at least one separate second pattern of weld-inhibitingmaterial, said first pattern corresponding to a predeterminedconfiguration of fluid passages and said second pattern defining a finpattern with said second pattern spaced from the peripheral edges ofsaid sheets, pressure welding said superposed sheets in the areas notseparated by said weld-inhibiting material, cutting at least one firstslit through the complementary portions of said panels, cutting at leasttwo spaced second slits at spaced points on said first slit and spacedapart a distance to provide substantial fin surface, said second slitstraversing said second pattern in a direction perpendicular to saidfirst slit and separating between adjacent second slits saidcomplementary portions to extend in opposite directions out of the planeof said panel whereby said separating forms an opening through saidpanel.

3. A method of making a finned hollow panel comprising interposingbetween superposed sheets of metal a first pattern of weld-inhibitingmaterial and at least one separate second pattern of weld-inhibitingmaterial, said first pattern corresponding to a predeterminedconfiguration of fluid passages and said second pattern defining a finpattern with said second pattern spaced from the peripheral edges ofsaid sheets, pressure welding said superposed sheets in the areas notseparated by said weldinhibiting material, cutting at least one firstslit through complementary portions of said panel adjacent said secondpattern, cutting at least two spaced second slits at spaced points onsaid first slit and spaced apart a distance equal to a major part of thelength of said first slit, said second slits traversing said secondpattern in a direction perpendicular to said first slit and beingintersected by said first slit, and separating all complementaryportions adjacent said second pattern and bounded by said first slit andbetween adjacent pairs of said second slits to extend in oppositedirections out of the plane of said panel whereby said separating formsan opening through said panel.

4. A method of making a finned hollow panel comprising interposingbetween superposed sheets of metal a first pattern of weld-inhibitingmaterial and at least one separate second pattern of weld-inhibitingmaterial, said first pattern corresponding to a predeterminedconfiguration of fluid passages and said second pattern defining a finpattern with said second pattern spaced from the peripheral edges ofsaid sheets, pressure welding said superposed sheets in the areas notseparated by said weldinhibiting material, cutting at least one firstslit through complementary portions of said panel adjacent said secondpattern, cutting two spaced second slits at the terminal portions ofsaid first slit, said second slit traversing said second pattern in adirection perpendicular to said first slit and being intersected by saidterminal portions and separating all complementary portions bounded bysaid first and both said second slits to extend in 0pposite directionsout of the plane of said panel whereby said separating forms an openingthrough said panel.

5. A method of making a finned hollow panel comprising interposingbetween superposed sheets of metal a first pattern of weld-inhibitingmaterial and at least one separate second pattern of weld-inhibitingmaterial, said first pattern corresponding to a predeterminedconfiguration of fluid passages and said second pattern defining a finpattern with said second pattern spaced from the peripheral edges ofsaid sheets, pressure welding said superposed sheets in the areas notseparated by said weldinhibiting material, cutting at least one firstslit through complementary portions of said panel adjacent said secondpattern, cutting two spaced second slits at the terminal portions ofsaid first slit, said second slit traversing said second pattern in adirection perpendicular to said first slit and being bisected by saidterminal portions, and separating all complementary portions bounded bysaid first and both said second slits to extend in opposite directionsout of the plane of said panel whereby said separating forms an openingthrough said panel.

References Cited in the file of this patent UNITED STATES PATENTS

1. A METHOD OF MAKING A FINNED HOLLOW PANEL COMPRISING INTERPOSINGBETWEEN SUPERPOSED SHEETS OF METAL A FIRST PATTERN OF WELD-INHIBITINGMATERIAL AND AT LEAST ONE SEPARATE SEECOND PATTERN OF WELD-INHIBITINGMATERIAL, SAID FIRST PATTERN CORRESPONDING TO A PREDETERMINEDCONFIGURATION OF FLUID PASSAGES AND SAID SECOND PATTERN DEFINING A FINPATTERN WITH SAID SECOND PATTERN SPACED FROM THE PERIPHERAL EDGES OFSAID SHEETS, PRESSURE WELDING SAID SUPERPOSED SHEETS IN THE AREAS NOTSEPARATED BY SAID WELDINHIBITING MATERIAL, AND CUTTING AT LEAST ONEFIRST SLIT THROUGH THE COMPLEMENTARY PORTIONS OF SAID PANEL ADJACENTSAID SECOND PATTERN, CUTTING AT LEAST TWO SPACED SECOND SLITS AT SPACEDPOINTS ON SAID FIRST SLIT AND SPACED APART A DISTANCE TO PROVIDESUBSTANTIAL FIN SURFACE, EACH OF SAID SECOND SLITS TRAVERSING SAIDSECOND PATTERN LATERALLY RELATIVE TO SAID FIRST SLIT, AND SEPARATINGBETWEEN ADJACENT SECOND SLITS SAID COMPLEMENTARY PORTIONS TO EXTEND INOPPOSITE DIRECTIONS OUT OF THE PLANE OF SAID PANEL WHEREBY SAIDSEPARATING FORMS AN OPENING THROUGH SAID PANEL.